ELBOW DISLOCATIONS - SECOND MOST COMMON LARGE JOINT
Posterolateral Most Common | LCL Always Injured | Early Motion Essential
CLASSIFICATION
Critical Must-Knows
- Posterolateral is the most common direction (90%)
- LCL complex always injured - primary lateral restraint
- Simple dislocations usually stable after reduction
- Complex patterns - terrible triad, coronoid, Monteggia variant
- Early motion is essential to prevent stiffness
Examiner's Pearls
- "LCL fails first, then anterior capsule, then MCL (outside-to-inside pattern)
- "Simple dislocations: if stable through 30-130° = non-operative
- "Check for associated fractures - radial head, coronoid are commonly missed
- "PLRI (posterolateral rotatory instability) is chronic sequela of LCL injury
Critical Elbow Dislocation Exam Points
Simple vs Complex
Simple = no fracture, ligament injury only. Typically stable after reduction with early motion. Complex = with fracture(s), includes terrible triad, requires addressing all structures.
Horii Circle
Soft tissue disruption pattern: LCL complex fails first (Stage 1), then anterior/posterior capsule (Stage 2), then MCL (Stage 3). Understanding this helps guide treatment.
Stability Assessment
After reduction, test stability under fluoro. Stable through 30-130° arc = non-operative. If redislocates before 60° extension = likely needs surgery.
Early Motion Critical
Stiffness is the enemy. Start motion within 1 week for simple dislocations. Prolonged immobilization leads to contracture. Use hinged brace if stability concerns.
Quick Decision Guide
| Pattern | Key Finding | Treatment |
|---|---|---|
| Simple dislocation | Stable after reduction (30-130°) | Early ROM in hinged brace, non-operative |
| Simple dislocation | Unstable after reduction | Consider operative LCL repair |
| Terrible triad | Dislocation + radial head + coronoid | Fix/replace RH, repair LCL, +/- coronoid |
| Radial head fracture-dislocation | Mason IV | Address radial head + ligaments |
| Anterior dislocation | Olecranon impales trochlea | Reduce carefully, assess for olecranon fracture |
| Divergent dislocation | Radius and ulna separate | Reduce, high likelihood of instability |
| Chronic dislocation | Unreduced over 3 weeks | Complex reconstruction required |
HORII - Circle of Instability
Memory Hook:HORII described the circle - injury moves from lateral (outside) to medial (inside)
REDUCE - Reduction Steps
Memory Hook:REDUCE the elbow with controlled technique
STABLE - Post-Reduction Assessment
Memory Hook:Is the elbow STABLE? Test it thoroughly
TERRIBLE TRIAD - Components and Treatment
Memory Hook:The TERRIBLE TRIAD requires systematic treatment of all components
Overview and Epidemiology
Elbow dislocations are the second most common large joint dislocation after the shoulder. They range from simple ligamentous injuries to complex fracture-dislocations with significant instability.
Mechanism of injury:
- Fall on outstretched hand (FOOSH) - most common
- Axial load with elbow slightly flexed
- Valgus and supination moment
- Creates posterolateral dislocation
- Direct trauma - less common
- Sports injuries - common in young adults
- Motor vehicle accidents - often high-energy, complex patterns
FOOSH Mechanism
The classic mechanism is a fall on outstretched hand with the elbow in slight flexion. The axial load creates a valgus and supination moment, driving the ulna posterolaterally relative to the humerus. This explains why posterolateral dislocation is most common.
Types:
- Simple (50-60%): No associated fracture, ligament injury only
- Complex (40-50%): With associated fracture(s)
- Terrible triad
- Radial head fracture-dislocation
- Coronoid fracture-dislocation
- Transolecranon fracture-dislocation
Anatomy and Biomechanics
Bony anatomy:
- Ulnohumeral joint: primary elbow stability (hinge)
- Radiocapitellar joint: secondary stabilizer
- Coronoid: anterior buttress of ulnohumeral joint
- Olecranon: posterior buttress
- Trochlea: articulates with greater sigmoid notch
Ligamentous anatomy:
Lateral Collateral Ligament (LCL) Complex:
- Lateral ulnar collateral ligament (LUCL) - most important component
- Origin: lateral epicondyle
- Insertion: supinator crest of ulna
- Primary restraint to posterolateral rotatory instability (PLRI)
- Radial collateral ligament (RCL) - blends with annular ligament
- Annular ligament - stabilizes radial head to ulna
Medial Collateral Ligament (MCL) Complex:
- Anterior bundle - most important
- Origin: medial epicondyle
- Insertion: sublime tubercle
- Primary valgus stabilizer
- Posterior bundle - tightens in flexion
- Transverse ligament - minimal contribution
O'Driscoll's Horii Circle
The soft tissue injury in elbow dislocation follows a predictable pattern described by the Horii circle. Disruption proceeds from lateral to medial: Stage 1 (LCL), Stage 2 (anterior/posterior capsule), Stage 3 (MCL). The LCL complex is ALWAYS injured in posterolateral dislocation.
Stages of instability (O'Driscoll):
- Stage 1: PLRI - LCL disruption, elbow subluxes posterolaterally
- Stage 2: Incomplete dislocation - capsule disrupted, elbow perches
- Stage 3A: Complete dislocation - MCL posterior bundle torn
- Stage 3B: Gross instability - entire MCL torn (anterior bundle)
Static vs dynamic stabilizers:
- Static: ligaments, bony congruity
- Dynamic: muscles crossing elbow (triceps, biceps, brachialis, flexors/extensors)
Classification Systems
Primary Classification
| Type | Definition | Incidence |
|---|---|---|
| Simple | No fracture, ligament injury only | 50-60% |
| Complex | With associated fracture(s) | 40-50% |
Simple dislocation:
- Ligamentous injury only
- Usually stable after closed reduction
- Excellent prognosis with early motion
Complex dislocation:
- Fracture + dislocation
- Includes terrible triad, radial head, coronoid patterns
- Usually requires operative treatment
- Higher complication rates
Classification into simple vs complex guides treatment approach and prognosis.
Clinical Presentation and Assessment
History:
- Mechanism of injury
- Any spontaneous reduction
- Previous elbow problems
- Time since injury
- Hand dominance, occupation
Physical examination:
Physical Examination Findings
| Finding | Significance | Action |
|---|---|---|
| Obvious deformity | Unreduced dislocation | Assess NV, reduce urgently |
| Olecranon prominence posteriorly | Posterior dislocation | Confirm with X-ray, reduce |
| Vascular compromise | Arterial injury/kinking | Urgent reduction |
| Nerve deficit (median/ulnar) | Nerve injury/entrapment | Document, usually resolves with reduction |
| Open wound | Open dislocation | Antibiotics, urgent OR |
| Severe swelling | High energy, compartment risk | Monitor compartments |
Pre-reduction assessment:
- Neurovascular status - median, ulnar, radial nerves; brachial artery
- Skin integrity - open vs closed
- Associated injuries - ipsilateral limb
- Deformity pattern - helps predict direction
Neurovascular Injury
Document neurovascular status before and after reduction. The ulnar nerve is most commonly injured (transient paresthesias in 10-20%). Brachial artery injury is rare but can occur, especially with anterior dislocations or open injuries.
Investigations
Pre-reduction imaging:
Standard views:
- AP elbow (or attempt)
- Lateral elbow
- Often difficult to obtain true views due to deformity
Radiographic assessment:
- Confirm dislocation and direction
- Look for associated fractures (radial head, coronoid)
- Assess any bony fragment position
Don't Delay Reduction
Do not delay reduction waiting for imaging if neurovascular compromise is present. A single lateral view can confirm dislocation. Reduce urgently, then obtain post-reduction imaging.
Post-reduction imaging:
Essential:
- AP and lateral elbow - confirm concentric reduction
- Look carefully for:
- Radial head fracture (often subtle)
- Coronoid fracture (often seen on lateral)
- Any joint widening suggesting interposed fragments
- Concentric reduction (radiocapitellar alignment)
CT imaging:
Indications:
- Suspected associated fracture not clear on X-ray
- Complex dislocation patterns
- Surgical planning
- Any joint incongruency on plain films
CT assessment:
- Fracture characterization (radial head, coronoid)
- Fragment count and size
- Associated injuries
Management
Reduction technique:
- Adequate analgesia/sedation (or general anesthesia)
- Assistant for counter-traction
- Fluoroscopy available if possible
- Document pre-reduction neurovascular status
- Patient supine, arm abducted
- Assistant holds upper arm for counter-traction
- Operator controls forearm
- Apply longitudinal traction along forearm
- Slight supination to correct rotational component
- Flex elbow while applying pressure to olecranon
- May need brief hyperextension to unlock coronoid
- Guide olecranon over trochlea into reduced position
- Palpable/audible clunk confirms reduction
- Confirm reduction with fluoroscopy/X-ray
- Test stability through ROM
- Document neurovascular status
- Splint in stable position
Reduction Technique
For posterolateral dislocation: Apply longitudinal traction with the forearm supinated (corrects the lateral rotation). Apply pressure to olecranon while flexing the elbow. The olecranon slides over the trochlea and reduces with a palpable clunk.
Post-reduction stability assessment:
After reduction, assess stability under fluoroscopy:
-
Flexion-extension arc: Move through ROM
- Note angle at which elbow redislocates
- Stable if maintains reduction 30-130°
- Unstable if redislocates before 60° extension
-
Valgus stress test: Test MCL integrity
-
Varus stress test: Test LCL integrity
-
Lateral pivot shift (if awake): Tests for PLRI
Key Stability Threshold
If the elbow is stable through 30° extension, it can be managed non-operatively with early motion. If it redislocates before 60° extension, operative stabilization is usually needed.
Surgical Technique
Kocher (Lateral) Approach
Indications:
- LCL repair
- Radial head fixation/replacement
- Lateral coronoid access
Technique:
- Incision from lateral epicondyle to ulna
- Identify anconeus-ECU interval
- Elevate anconeus from posterior ulna
- Expose LCL complex (usually avulsed from lateral epicondyle)
- Address radial head
- Repair LCL with suture anchors
The lateral approach provides excellent access to the lateral stabilizers.
Complications
Complications of Elbow Dislocation
| Complication | Incidence | Management |
|---|---|---|
| Stiffness | 20-30% | Early motion, physio, capsular release if severe |
| Recurrent instability | 1-2% simple, higher complex | LCL reconstruction, address all structures |
| Heterotopic ossification | 5-10% | Prophylaxis (indomethacin), excision if limiting |
| Post-traumatic arthritis | 5-10% | Activity modification, eventual arthroplasty |
| Chronic PLRI | Variable | LCL reconstruction |
| Nerve injury (ulnar) | 10-20% transient | Usually resolves, may need exploration |
| Vascular injury | Rare | Urgent vascular repair |
| Compartment syndrome | Rare | Emergency fasciotomy |
Stiffness:
- Most common complication
- Prevention is key - early motion
- Flexion contracture most common pattern
- Treatment: physiotherapy, dynamic splinting, surgical release
Posterolateral rotatory instability (PLRI):
- Chronic sequela of untreated/inadequately healed LCL
- Patient has apprehension or frank instability
- Treatment: LCL reconstruction
Stiffness Prevention
The elbow is prone to stiffness after injury. Most activities require 30-130° arc and 50° supination/pronation. Early motion within the first week significantly reduces stiffness risk. A functional arc for most activities is 30-130°.
Heterotopic ossification:
- Risk factors: head injury, burns, delayed surgery, aggressive physio
- Prophylaxis: indomethacin 25mg TDS x 3 weeks (or radiation)
- Excision if mature and limiting function
Postoperative Care and Rehabilitation
Simple dislocation (non-operative):
- Posterior splint at 90°
- Elevation, ice
- Finger motion
- Convert to hinged elbow brace
- Begin active ROM in brace
- Flexion-extension exercises
- Light supination/pronation
- Progressive ROM
- May wean from brace if stable
- Target functional ROM
- No valgus/varus stress
- Full ROM expected
- Begin strengthening
- Progressive activity
- May resume light sport
- Full activity
- Sports clearance
- Final outcome assessment
Post-operative (LCL repair/complex):
- More protected initially
- Hinged brace with extension block if needed
- Motion started early but within safe arc
- Progress based on stability and healing
Functional ROM
Functional elbow ROM for most activities: 30-130° flexion-extension and 50° supination/pronation. Focus rehabilitation on achieving this functional arc. Some terminal limitation may be well-tolerated.
Outcomes and Prognosis
Outcomes by type:
| Type | Good/Excellent | Key Factors |
|---|---|---|
| Simple, stable | 90-95% | Early motion critical |
| Simple, unstable treated | 85-90% | Quality of repair |
| Complex (terrible triad) | 70-80% | Address all structures |
| Complex (other) | 60-80% | Pattern-dependent |
Prognostic factors:
- Simple vs complex (simple better)
- Time to reduction
- Time to motion initiation
- Quality of reduction
- Associated injuries
- Patient compliance
Simple Dislocation Prognosis
Simple elbow dislocations that are stable after reduction have excellent prognosis (over 90% good/excellent outcomes) with early motion protocol. The key is avoiding prolonged immobilization.
Evidence Base
- Described stages of elbow instability (Horii circle) - injury progresses from lateral to medial. LCL disruption is stage 1, followed by capsule, then MCL.
- Simple elbow dislocations treated non-operatively with early motion had excellent outcomes. Prolonged immobilization increased stiffness without improving stability.
- 52 patients with elbow dislocation - 60% had residual symptoms. Flexion contracture most common. Early motion correlated with better outcomes.
- Standard protocol for terrible triad: fix/replace radial head, repair LCL, fix coronoid if needed. 72% good/excellent results.
- LCL reconstruction for chronic PLRI using tendon graft produces reliable results. Most patients achieve stable, functional elbow.
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Simple Posterior Elbow Dislocation
"A 25-year-old man falls while skateboarding, landing on his outstretched hand. He presents with obvious elbow deformity. X-rays confirm a posterior elbow dislocation with no fracture. How do you manage this injury?"
Scenario 2: Unstable Simple Dislocation
"You reduce a simple posterior elbow dislocation in a 35-year-old woman. After reduction, under sedation, you assess stability. The elbow redislocates when you extend beyond 50 degrees. What is your management?"
Scenario 3: Terrible Triad Injury
"A 45-year-old woman falls down stairs. Her elbow was dislocated and has been reduced in the emergency department. CT shows a Mason Type III radial head fracture with 5 fragments and a small coronoid tip fracture. How do you approach this injury?"
MCQ Practice Points
Direction Question
Q: What is the most common direction of elbow dislocation? A: Posterolateral - accounts for approximately 90% of elbow dislocations. The mechanism (FOOSH with valgus and supination moment) drives the ulna posterior and lateral to the humerus.
Classification Question
Q: What differentiates simple from complex elbow dislocation? A: Simple = no fracture (ligament injury only). Complex = with associated fracture (radial head, coronoid, olecranon). Simple dislocations are usually stable after reduction with excellent prognosis.
Horii Circle Question
Q: In what order do structures fail in posterolateral elbow dislocation? A: According to the Horii circle, injury progresses from lateral to medial: Stage 1 (LCL complex), Stage 2 (anterior/posterior capsule), Stage 3 (MCL). The LCL is always injured first.
Stability Question
Q: What is the threshold for stable vs unstable simple elbow dislocation? A: If the elbow maintains reduction through 30° extension to full flexion, it is considered stable for non-operative treatment. If it redislocates before 60° extension, operative stabilization is usually recommended.
Complications Question
Q: What is the most common complication of elbow dislocation? A: Stiffness - occurs in 20-30% to some degree. Prevention through early motion is key. Prolonged immobilization (greater than 3 weeks) significantly increases stiffness risk.
Australian Context
Epidemiology:
- Common in contact sports (football, rugby)
- Skateboarding and cycling falls
- Workplace injuries
- Motor vehicle accidents
Management considerations:
- Most hospitals can manage simple dislocations
- Complex patterns benefit from subspecialty input
Transfer considerations:
- Complex dislocations to trauma centres
- Access to hinged external fixators varies
- Terrible triad benefits from elbow subspecialty
Exam Context
Be prepared to discuss reduction technique, stability assessment, simple vs complex classification, and terrible triad management. Understanding the Horii circle and when to operate are key viva topics.
ELBOW DISLOCATIONS
High-Yield Exam Summary
CLASSIFICATION
- •Simple = no fracture, ligament injury only
- •Complex = with fracture(s)
- •Posterolateral = 90% (most common)
- •LCL always injured in posterolateral
HORII CIRCLE (INJURY PROGRESSION)
- •Stage 1: LCL complex (lateral)
- •Stage 2: Anterior/posterior capsule
- •Stage 3A: Posterior MCL
- •Stage 3B: Entire MCL (medial)
REDUCTION TECHNIQUE
- •Document NV status before and after
- •Adequate sedation essential
- •Traction + supination + olecranon pressure + flex
- •Confirm with X-ray
STABILITY ASSESSMENT
- •Test ROM under sedation/anesthesia
- •Stable if maintains reduction to 30° extension
- •Unstable if redislocates before 60° extension
- •Unstable = likely needs operative repair
SIMPLE DISLOCATION MANAGEMENT
- •If stable: early motion, hinged brace
- •Begin ROM within first week
- •Avoid prolonged immobilization (greater than 3 weeks)
- •If unstable: LCL repair
TERRIBLE TRIAD PROTOCOL
- •Dislocation + radial head + coronoid + LCL
- •1. Fix/replace radial head
- •2. Repair LCL (always injured)
- •3. Fix coronoid if still unstable
- •4. Consider hinged fixator if needed